The present invention relates to a roll feed device for automatically supplying material to a press.
In an automatic operation of a press, a roll feed which supplies material to the press dies at predetermined intervals is an indispensable mechanism. It comprises two rolls, one of which is a main feed roll connected to a rotating and driving mechanism, while the other serves to support the material pressed by the main feed roll and inserted between the two rolls as it is fed to the press dies. The roll feed device is usually mounted on the press, and the main feed roll is driven in a predetermined timed relationship to the reciprocating motions of the slide of the press. In supplying the material to the press dies, the main feed roll rotates intermittently and in one rotational direction so that the material is supplied in one direction only. Feeding of the material by such a roll feed device is widely employed because the device is an automatic device having great versatility and the use of which is not limited by the width or the thickness of the material.
An angle indexing cam, which is a mechanism for transforming the continuous motion associated with a crank shaft which drives the press slide into an intermittent motion for driving the main feed roll, has a smooth motion from the stopped condition to the rotating condition and back to the stopped condition, and the shape of this cam provides a high dependability of the precision of the feeding operation by the roll feed. Since the angle through which the angle indexing cam rotates during one pitch is fixed, the conventional methods for changing the lengths of the material fed by the roll feed device have been methods such as exchanging the feed rolls of the roll feed device or changing variable speed gears provided between an output shaft of the angle indexing cam and a shaft on the main feed roll.
However, these conventional techniques are disadvantageous in that many lengths of material to be fed cannot be accommodated and also it takes a long time for changing and adjusting the operation of the feed device.
Moreover, among the above-mentioned techniques, in the method of exchanging the feed rolls there are the drawbacks that the thickness of the material fed may be changed when the rolls are changed, and that it is necessary to adjust a releasing device for temporarily discontinuing the urging of the two rolls against each other.
In the method of changing the variable speed gears, it is usually the practice to provide an intermediate gear between the output shaft of the angle indexing cam and the shaft of the main feed roll, but in variable speed gears in which the positions of the shafts are fixed and the engaged gears are simultaneously exchanged, it is not possible to employ many kinds of variable speed gears because the combination of the gears is limited due to modules.